This invention relates to the manufacture of optical fibres, particularly to coating a fibre.
An optical fibre for telecommunications comprises a glass fibre drawn from a thicker glass rod (preform) in a high temperature furnace. The diameter of the fibre is measured by a monitor and interfaced with the speed at which the fibre is drawn in order to control the diameter of the fibre. It is also arranged to control movement of the preform chuck to maintain the position of the fibre-line below the furnace.
Bare glass fibre has a strength which is easily degraded by the smallest of surface flaws. At least one durable protective coating is applied as soon as practical to the bare glass fibre to preserve the near flawless surface of a freshly drawn fibre. To give maximum protection any coating must be concentric about the fibre. A non-contacting concentricity monitor is used to monitor, and provide information to adjust the coating concentricity.